Disulfides as synergists for 2, 4-d



Patented Feb. 2, 1954 L yleeD'; GoodhuauBartlesville, okla assig'nortto Phillips Petroleunn Company; a corporation of Delaware NoD'rawing.v Application :March; 3-1;, 1950; SeriarNo. 153,299,

10::Olaims;

Thisinvention re1ates== to the use of dialkyr disulfides as synergists for increasing the phyto toxicity" of" 2,4-dichlorophenoxyacetic acid and its deriva-tivesr I have now discovered that dialkyldisulfides are effective synergists-for increasingthe h erbi cidal' action of 2,4-dichlorophenoxyacetic' acid anditsderivatives: The compoundsof the present invention can be representedby the-general formula wherein R and R are selected" from straight andbranched chairr alkyl" groups; each containing from eight-totwel ve carbon atoms, and can be different.

The term synergistas. employedin this application. refers to a material which will facilitate entrance of 2A dichloroph'enoxyacetic acid (or other plant hormone) to the plant without itself rendering anweffiectowhich hinders or prevents absorption. and/or translocation of said hormone.

The compounds of the presentinventioncan beemployed in admixture with 2',4 dichlrophenoxyaceticacid and its derivatives such as, the esters and salts. Examplesuof esters includethe. methyL-butyl andisopropyl compounds. Typical salts includethe' sodium salt; and .the.amine,salts, such-as the diethanoland triethanolgamine salts.

Followingv commonlusage, the termv 2550; will be used hereinafter. as ageneric, term covering thesparentf acid. and its derivatives. 2AA) has been widely usedcfor, selective: weed killing. pur. poses;

their phytotoxic action-isdi-rected substantially exclusively to plants oitheebroad-leaied or di cotyledonous type; having: littleif efiect: onnarrowleafedv or monocotyledonous plants;

These-compounds'areaabsorbed by the leaves of dicotyledons and after being absorbed are translocatedto other-parts of the plantincludings the root systemthusk-illing theeplant from within. These compounds have found wide application as herbicides because in addition to killing" that These compounds are termed? selective; herbicides because inordinary concentrationsan inert solvent or carrier.

applied to areas in which both desirable plants and"those considered as weeds are growing. Forzexamplait. is important that 2,4-D isynergists be .snbstantially-'non-toxicto= lawn grasse when I la-D compositions containing synergists are used'zfor selectively removing weeds such as dandelions, etc: from-lawns: Further: 2;4-D syn= ergists should be readily absorbedby the plant and capable of rapid 'transl'ocation thereth'rougli;

A common methodnow inuSe- 'f 0-1 'app1ying 2,443 to plants comprises dissolving the com-- pound in a suitable sol-ventsuclr as diesel oil-,2 emulsifying said solution in water andapplying the emulsion as. a spray- However, diesel oil and many other; solvents: of-Lthistype-often proavide a ,burningsactiont which may be, sufficient in many instances: to, prevent the effective trans: location of v. the active. ingredient, 2A4). In. addition these, solvents display varying degrees of. toxicityto. nearly all plants-and some damage. may come. totdesirable plants when. herbicides containing such, solvents are employedfor: selectti-velyremovingweeds; from. cultivated. crops; Since my novel activatorsareeexcellentsolvents- L for 2,4-D, they may be used to replace diesel oil when compounding emulsions-for selective weedpurposess Furthermoraisince novel activators motif-only: increase? the; eirectivenessgof: as p; but; aiscr. haves: a; low' toxicity. to pIants-,; numeronscadvantagessaaza obtained bmusin gzthese cpmpoundstin azd'inhdzureewithflg'l-Dr For: examples the :same eifectcmay: be obtained by using: a smaller amount not zi-i-Dfiniadmsixtureewitlr the present activators ,thancwhen using 2,4-D in In many instances the-"amount 'of 2-34 1)maybe-reduced by as much as 90 percent-j that 1s;- one-tenth the amount-' of" 234 13 inadmixture with? my novel-= activators provides sub'stantially the same Herbi ci da efi ect'asQA -D in-an inert carriercrsol-vent? iiicases Where it isnot desirable-- to reduce the amount of 2 A -D -when-* using my activators; the" eifectiveness" of 21I4 -Dis:increased and the plants are" killed in a shorter period with lessrov;th-'afterapplication: When so operatingplants-WHY often-1. be killed in per" cent" of}? the time normally required when using" 2Z4-'-D -'wi-tl'iout activators.

When operating in zthesmanner described above with the. compounds of the, present invention,

2,4-dichloroplienoxyacetic acid'or a derivative thereof is dissolved in a disulfide selected from the group disclosed hereinbefore in a ratio of from .01 to .5 pounds of 2,4-dichlorophenoxyacetic acid or derivative per pound of disulfide.

This solution is next emulsified in water and applied at a rate of 0.1 to 5 pounds of 2,4-dichlorophenoxyacetic acid or derivative per acre. The amount of water employed will usually be in the range from 5 to 50 gallons per acre.

It is an advantage of the compositions of the present invention that they are particularly effective against woody plants such as Jack oak and the like.

Example I The following is a comparison of the action of 2,4-D in Soltrol* 140 (a non-toxic solvent) and di-tertiary-octyl disulfide at four concentrations. One cc. of each solution was emulsified in 20 cc. of water with 5 drops of Triton X 100 (alkylated aryl polyether alcohol). This emulsion was then sprayed on vigorous string bean plants. The eifect of di-tert-octyl disulfide in reducing the terminal weight growth is clearly evident from the following table.

Wt. of tConcen-f gerrntiliialt ration row a Test No. Solvent 2,44) End of 14 Percent Days (Gms).

Di-tert-octyl disulfide 0. l 2. l d 0. 01 S. 0. 001 ll. 1 0. 0001 15. 0 0. l 6.0 0. 01 21. 2 0.001 25.5 0. 0001 18. 4

*Solt-rol 140 is an isoparafiinic hydrocarbon fraction boiling between l 360 and 410 F. at 760 mm. and having little if any phytotoxic effect.

The epinasty (curling and bending down) was much greater in tests 2, 3 and 4 where di-tert ootyl disulfide was used with 2,4-D than in tests 6, 7 and 8 where Soltrol 140 was used as the solvent. The epinasty produced by 2,4D dissolved in the disulfide was equivalent to the epinasty produced by approximately ten times the amount of 2,4-D in the inert solvent Soltrol 140, in the tests referred to above.

Example II The tests of Example I were repeated using di-tert-dodecyl disulfide instead of di-tert-octyl disulfide. The synergistic effect of this disulfide was nearly the same as noted in Example I.

The epinasty was substantially equivalent to that of a solution of di-tert-octyl disulfide having /5 the concentration of 2,4-D.

Example III Example IV Afive per cent solution of di-tert-octyl-disulfide in Soltrol 140 (an isoparaffinic hydrocarbon boiling between 360 and 410 F. at 760 mm.) was sprayed on mature cotton plants, at a rate of pounds of disulfide per acre in a field test. The plants were still alive fourteen days after application of the disulfide solution.

Reasonable variation and modification are possible within the scope of the foregoing disclosure and the appended claims to the invention the essence of which is that dialkyl disuliides have been found to synergize 2,4-dichlorophenoxyacetic acid and its derivatives, which are set forth in U. S. Patent 2,390,941, issued December 11, 1945.

I claim:

1. A herbicidal composition of matter comprising 2,4-dichlorophenoxy acetic acid as an effective ingredient thereof and di-tert-octyl disulfide as a synergist therefor.

2. An improved method for killing weeds which comprises applying to said weeds a composition according to claim 1.

3. A herbicidal composition of matter comprising 2, i-dichlorophenoxyacetic acid as an effective ingredient thereof and ditert-dodecyl disulfide as a synergist therefor.

4. An improved method for killing weeds which comprises applying to said weeds a composition according to claim 3. i

5. A. herbicidal composition of matter comprising a compound selected from the group consisting of 2,-dichlorophenoxyacetic acid and its salts and esters and a compound selected froml. A composition according to claim 5 wherein .01 to 0.5 pounds of a compound selected from the group consisting of 2,4-dichlorophenoxyacetic acid and its salts and esters is dissolved in about one pound of said selected compound.

8. An improved method for killing weeds which comprises applying in a proper manner to said weeds a composition according to claim 7.

9. A herbicidal composition of matter comprising a compound selected from the group consisting of 2, i-dichlorophenoxyacetic acid and its salts and esters and di-tert-octyl disulfide.

10. A herbicidal composition of matter comprising a compound selected from the group consisting of 2, i-dichlorophenoxyacetic acid and its salts and esters and di-tert-dodecyl disulfide.

LYLE D. GOODHUE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,986,218 Remy Jan. 1, 1935 2,043,941 Williams June 9, 1936 2,390,941 Jones Dec. 11, 1945 OTHER REFERENCES Science, Oct. 16, 1936, page 356. 

5. A HERBICIDAL COMPOSITON OF MATTER COMPRISING A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 2,4-DICHLOROPHENOXYACETIC ACID AND ITS SALTS AND ESTERS AND A COMPOUND SELECTED FROM THE GROUP OF COMPOUNDS WHICH CAN BE REPRESENTED BY THE GENERAL FORMULA 